Poekilogainiiiarus, Echinogaminanis 479 



piriform (in figure oblong oval). Gnathopod 2. 6*^' Joint narrowly oblong, 

 nearly 3 times as long as o*^ Joint. Peraeopods 3 — 5, 2'^ Joint raoderately 

 broad, in peraeopod 5 with 7 or 8 rather long setae ou front and bind 

 margins (in figure rather wider above than below, bind and lower margins 

 nearly straight). Uropod 1 reacbing mucb beyond uropod 2, but scarcely 

 to raiddle of uropod 3. Uropod 3 ^^ — ^.-t ^s long as body. Colour bright 

 yellow with bright brown spots. L. about 14 mm. 



Lake Baikal. Depth 100—200 m. 



4. P. araneolus (Dyb.) 1874 Gammarus a. -\- G. a. var. quinquefasciaius -j- 

 6r. a. var. ephippiatus, B. Dybowsky in: Horae Soc. etit. Ross., v. 10 suppl. p. 106 t. 11 

 f. 3; p. 107 t. 11 f. 7; p. 107 t. 11 f. 8 | 1899 Foekilogammarus a., T. Stebbing in: Tr. 

 Linn. Soc. London, ser. 2 v.7 p. 428 | 1893 Gammarus fluviatilis (part.)?. G. pictus 

 (part.)?, A. DellaValle in: F. Fl. Neapel, Z7.20 p. 927; p. 928, 930. 



All Segments of peraeon and pleon carrying short dorsal setae or very 

 thin spinules; on peraeon Segments 1 — 6 the setae geuerally on the bind 

 margin, on peraeon segment 7 and pleon segments 1 — 6 over all the 

 dorsal surface (fewer setae in var. ephippiatus). Head as in P. orchestes. 

 Eyes large, prominent, ovate, slightly narrowed below, black. Antenna 1 

 only half as long asbody, twice as long as antenna 2, 2*^ Joint a little shorter 

 than 3*^, flagellum about twice as long as peduncle, 19— 25-jointed, accessory 

 flagellum 3- or 4-jointed. Antenna 2, ultimate and peniütimate joints of 

 peduncle subequal, flagellum shorter than peduncle, ö — 8-jointed. Gnathopod 1, 

 6*h Joint piriform. Gnathopod 2, 5*'^ Joint not elongate, 6*^^^ oblong, in ö 

 wideniug to the palm. Peraeopods 3 — 5, 2*^ Joint tolerably broad, front 

 and bind margins feebly couvex, bind margin with short setae. Uropod 1 

 reacbing eud of uropod 3, uropod 2 only end of peduncle of uropod 3. 

 Uropod 3 tolerably long, ^;, as long as body. Colour bright green or bright 

 greenish yellow with brownish yellow spots; in var. quinquefasciaivs, trans- 

 versely banded, head and peraeon segments 1 — 3 reddish brown, segments 4 

 and 5 bright yellow, segments 6 and 7 and pleon segments 1 and 2 brown, 

 pleon segments 3 — 6 and telson bright yellow, uropod 3 brown; in var. 

 ep/iippiatus brownish yellow or dark green, with a saddle-like brightening 

 of peraeon segments 6 and 7. L. 11 — 14 mm. 



Lake Baikal. Depth 10—50 m. 



46. Gen. Echinogammarus Stebb. 



1793 [Subgen.] GammareUus (part.). J. F.W. Herbst, Naturg. Krabben Krebse, v.2 

 p. 106 ! 1899 Echinogammarus, T. Stebbing in: Tr. Linn. Soc. London, ser. 2 v.7 p.428. 



In general like Gammarus (p. 460), but with dorsal spines on segments 

 anterior to pleon segment 4 (Fig. 89 p. 481), antenna 1 the longer, with 

 peduncle shorter than peduncle of antenna 2, and 6^^ Joint of gnathopod 1 

 almost always larger than that of gnathopod 2. 



27 acoepted and 1 doubtful species. 

 ' Synopsis of accepted speeies : 



Uropod 3, inner ramus mach less than half as 



long as outer — 2. 

 Uropod 3, inner ramus about half as long as 



outer — 10. 

 Uropod 3, inner ramus much more than half 



as long as outer — 14. 



